diff --git a/UPGRADE.md b/UPGRADE.md
index 15cec2d7..f58860fc 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -8,6 +8,15 @@ awareness about deprecated code.
 
 # Upgrade to 5.0
 
+## BC Break: `ObjectRepository::findBy()` `$orderBy` additionally accepts the `SortDirection` enum
+
+The `$orderBy` parameter of `findBy()` now also accepts the PHP 8.6 `SortDirection`
+enum, in addition to the `'asc'`, `'desc'`, `'ASC'` and `'DESC'` strings. The native
+signature is unchanged and strings remain accepted.
+
+Implementations of `ObjectRepository` must accept the enum and cannot declare a
+more restrictive type for `$orderBy`.
+
 ## BC Break: `ClassMetadata::getFieldValue()` and `setFieldValue()` are now required
 
 The methods `getFieldValue()` and `setFieldValue()` are now required by the
diff --git a/composer.json b/composer.json
index fb7ff509..a5a92959 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,8 @@
         "doctrine/coding-standard": "^14",
         "phpunit/phpunit": "^10.5.58 || ^12",
         "symfony/cache": "^4.4 || ^5.4 || ^6.0 || ^7.0 || ^8.0",
-        "symfony/finder": "^4.4 || ^5.4 || ^6.0 || ^7.0 || ^8.0"
+        "symfony/finder": "^4.4 || ^5.4 || ^6.0 || ^7.0 || ^8.0",
+        "symfony/polyfill-php86": "^1.41"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/ObjectRepository.php b/src/ObjectRepository.php
index fce86e96..b78920d7 100644
--- a/src/ObjectRepository.php
+++ b/src/ObjectRepository.php
@@ -4,6 +4,7 @@
 
 namespace Doctrine\Persistence;
 
+use SortDirection;
 use UnexpectedValueException;
 
 /**
@@ -38,9 +39,9 @@ public function findAll(): array;
      * an UnexpectedValueException if certain values of the sorting or limiting details are
      * not supported.
      *
-     * @param array<string, mixed>       $criteria
-     * @param array<string, string>|null $orderBy
-     * @phpstan-param array<string, 'asc'|'desc'|'ASC'|'DESC'>|null $orderBy
+     * @param array<string, mixed>                     $criteria
+     * @param array<string, string|SortDirection>|null $orderBy
+     * @phpstan-param array<string, 'asc'|'desc'|'ASC'|'DESC'|SortDirection>|null $orderBy
      *
      * @return array<int, object> The objects.
      * @phpstan-return list<T>